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PCV and ring seal

cheveslakr

cheveslakr

Veteran Member
Senior Member
A little background here.....this is in regards to my 327 in the Jeep. I did a refresh/rebuild on a good running engine that came in a different car I bought. Never put more than 100 miles on it, but it ran just fine. Needed a sbc for the Jeep so plucked this and opened it up, measured and observed, decided it needed nothing more than a backyard rebuild. .030 block. Honed, cleaned, new internals with cast pistons, cast rings, polished crank and rebuilt 492 angle plug heads. Runs great, but used a lot of oil. Have maybe 1200 miles on it and it's burned close to 4 qts of oil. No smoke, but does puff a bit on startup. Buddy that used his hone on this said it could be that it was running rich during break-in and the cast rings may seat, but it's a toss-up. Just did a leak down test, 4 cyl at 7%, 2 at 8%, 1 at 10%, 1 at 12%. So, looked a bit further and noticed that my valve cover didn't have the baffle under the pcv and it was dripping oil. This may be the sole reason for the consumption, currect?? I buttoned up the motor and am going to drive it today for at least 50 miles and check consumption. .. Plugs were really ugly, at least 6 of them, number 1 and 2 were fairly clean and cocoa brown. PCV is into the rear of the manifuld on a dual plane intake.
Thoughts??
 
Hmm, sounds more like valve stem seals. I've dealt with a couple that needed new seal and after they were replaced, oil consumption dropped bigtime and no smoke on startup.
 
Is the pcv hose very wet inside ? Can you replace the valve cover with one that has a baffle ?
Does the passenger valve cover have a hose to the air cleaner base ?
Nice simple video for anyone that needs a refresher - I did

 
I suck....probably should have mentioned I installed a baffle for the pcv and by listening while doing the leak down test, the valve stem seal, intake and exhaust were mostly silent and the dipstick was the noiseiest, but not bad at all. The numbers tell me engine has no major leaks correct? PCV is on pass side, rear, intake air breather on driver's front.
 
cheveslakr said:
I suck....probably should have mentioned I installed a baffle for the pcv and by listening while doing the leak down test, the valve stem seal, intake and exhaust were mostly silent and the dipstick was the noiseiest, but not bad at all. The numbers tell me engine has no major leaks correct? PCV is on pass side, rear, intake air breather on driver's front.
Click to expand...
LOL not sure but if Kevin is right, valve seals usually give a puff of smoke when you start it and then the smoke goes away ?
 
I thought the pcv on drivers side and air cleaner hose on passenger side was due to the direction of rotation of the crank ?
Yet yours are on the opposite sides ?
 
They are positive seals, new guides, new valves and done by the most trusted shop around. That's a new one on me, the rotation effects positioning of the pcv, not making sense in my mind, but will research.
 
cheveslakr said:
the rotation effects positioning of the pcv, not making sense in my mind, but will research.
Click to expand...
Found out it doesn't matter ! Some pcv's were installed in the block, so which valve cover is irrelevant.
But the other side must hook to air cleaner or fresh air (filtered).
 
Last edited:
Here's a leak-down test troubleshooting list
  • Intake valve : Air whistling out of the intake, carburetor or throttle body indicates a leak at the intake valve.
  • Exhaust valve : Air heard hissing out of the tailpipe, turbocharger or exhaust manifold means an exhaust valve leak.
  • Piston rings : Whistling or hissing out of the PCV valve, oil filler cap hole or dipstick tube means the air is pushing past the rings. Suspect ring or cylinder wall wear.
  • Head gasket : Air bubbles in engine coolant seen at the radiator filler cap could mean air escaping into the coolant past the head gasket.
  • Cracked cylinder head : Bubbles in coolant or coolant being pushed up out of the radiator neck can also indicate cracks in the cylinder head or cylinder walls.
www.mobil.com

How to do a leakdown test | Mobil™ Motor Oils

Before you tear down the engine, pinpoint where problems are by using these three steps to do an engine leakdown test.
www.mobil.com www.mobil.com
 
If air is mostly coming up through dipstick tube after reading Beths link sounds like rings didnt seat... yet ??
 
Nope, ring marker installed up. The numbers are at the high end of a tight motor. From what I know, the percentages closer to 20% leakage are indicatve of poor ring seal. That basis is relative to a properly prepped cylinder. Keep in mind, this is a old bore, no lip, no excessive wear, fresh hone. That would lead me to look for numbers similar to what I'm seeing.
 
Got back, checked 3 plugs, pretty much the same.....new plugs by the way. Took the pcv hose off and it was dry. I'm going to run this by my machinist soon.
 
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